Method of calcining gypsum rock and the like



C. R. BIRDSEY.

METHOD OF CALCINING GYPSUM ROCK AND THE LIKE.

APPLICATION FILED JULY 16.1917.

1,412,203. Patented Apr. 1.1, 192%.

UNITED STATES PATENT OFFICE.

CHARLES R. IBIRDSEY, OF HINSDALE, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS,

T0 UNITED STATES GYPSUM COMPANY,

OF ILLINOIS.

Application filed July 16,

v To all whom it may concern:

.Be it known that I', OHARLEs R. BIRDsEY, citizen of the United States, residing at Hinsdale, in the county of Du Page, State of Illinois, have invented certain new and useful Im rovements in the Methods of Calcining ypsum Rock and the like, of which the following is a description.

My invention relates to a new and novel process or method of calcining gypsum rock or like substances, and suitable apparatus for carrying out the method. In the manufacture of gypsum products, it has been found desirable and often necessary to make material which has widely different characteristics in its dry bulk and in the amount of water :which it will carry to bring it to a certain consistency. If gypsum rock is subjected to the proper temperature for the proper length of time, it is uniformly calcined entirely through the whole mass. To make material which has a low water carrying capacity, which in turn permits casting a mass which is dense in its nature, it is found. that the material should be ground very fine before it goes to the kettles or calciners which are used for calcination purposes, and then not to be reground after the calcination. In making material which has a very large dry bulk, with ability to carry a great amount of water inwet bulk, which would end in the mass having great plastic qualities but not very high structural strength, it is found that the material should be ground coarse before it goes to the calciners, and it is calcined in that condition and thereafter reground. I have found, however, that these two processes can be carried on together, the materials being separated after calcination, the coarser particles being preferably calcined without over burning of the finer particles. My invention has among its objects the method and the production of suitable apparatus for carrying out the method, thatis simple, economical, efficient and satisfactory. It has particularly as an object the production of the apparatus for carrying out the method or process, inwhich the fine and coarse particles canbe perfectly calcined together, thence separated as desired. It has also among its objects the production of apparatus for carrying out the process, to which desired proportions.

OF CHICAGO, ILLINOIS, CORPORATION METHOD OF CALGINING GYPSUM ROCK AND THE LIKE.

Specification of Letters Patent.

Patented Apr. 11, 1922.

1917. Serial No. 130,901.

the particles may be fed and the calcined products be discharged in substantially continuous streams of finished material, in the Many other objects and advantages will be obvious to those skilled in the art from the disclosure herein made.

T 0 this end my invention consists in the novel construction, arrangement and combination of parts herein shown and described, and more particularly pointed out in the claims.

In the drawings, wherein like reference characters indicate like or corresponding parts,

Figure 1 is a sectional View, partially diagrammatical, of my preferred form of apparatus for carrying out the method;

Figure 2 is a top elevation of the charging hopper; and I Figure 3 is a vertical sectional view, taken substantially on line 3-3 of Figure 1. v

Referring to the drawi s in which one embodiment of the invention is shown, 1 represents the calciner, which is preferably in the shape of a cylindrical drum, constructed of the desired material and of suitable size. The drum shown is provided with an inlet at one end for charging and with discharge outlet at the other, the same being supported in any desired manner. As shown it is rotatably supported and means provided for'rotati'ng the same as desired. Referring to Figure 1, 22 represents rollers or the equivalent, of which there may be any desired number of the desired size, which are arranged to support the drum as desired, usually adjacent the ends as shown. It will be noted by referring to the figure, that the inlet end of the drum is slightly higher than the outlet end, so. that the drum is slightly inclined, the purpose of this being hereafter described. The drum is preferably provided with channels 3-or equivalent means about the exterior thereof, arranged to cooperate with the rolls and maintain the drum against lengthwise movement or displacement. For driving the same, I provide annular gears 4 about the same which mesh with the pinions 5, driven b shaft 6, through the pulley 7 and belt 8, or equivalent means for the purpose. WIthm the drum may be arranged blades or shovels drum is rotated, and stir the same.

9, the purpose of these being to feed the material from the inlet end to the outlet as the They may be of any suitable design, and as many employed as found necessary.

The preferred method of heating the contents of the drum is to pass heatedair or gases therethrough, and for this purpose, I have provided a furnace or heater 10, preferably at the inlet end, together with suitable means for drawing the heated gases through the drum and controlling the heating, as will be more fully described hereafter. The same is fitted substantially close to the end of the drum so all heat will enter the drum and very little cold air. While any style of heater suitable may be-employed,

the heater shown is simple and has been found Very satisfactory for the purpose, and the heat is welldistributed throughout the drum. I

The materials are fed into the drum by means of a chute or spout 12 or its equivalent,

arranged at the inlet or charging end, the chute being connected with a hopper 13, or the equivalent, so that material dumped or discharged into the hopper will be fed into the drum. In the preferred construction, I employ suitable feeding means between the hopper 13 and the chute 12, so that the rate of feeding of the material from the hopper intothe chute and drum may be controlled or regulated as desired. For this purpose a spiral screw member 14 is shown, which may be driven by the pulley 15 or equivalent means. 1 Obviously, by regulating the speed of the screw 14, the material may be fed into the drum in such quantities in a determined time as may be desired. It is also continuously and-evenly fed into the drum, although the hopper may be filled or charged intermittently.

In the particular construction illustrated, a receiving chute 17 is arranged at the discharge end of the drum, the same terminating in a well or pocket from which the material which has been calcined is carried to the separator. For separating the fine from the coarser particles of the mass to produce two products, I have shown a screen 18 of the desired material and of suitable mesh, the material being conducted from the well by the elevating buckets 19 or the equivalent, arranged within a housing 20 as shown. The elevator discharges the calcined'material onto the screen or separator 18, through which the fine material passes and falls into a hopper 21. Hopper 21 may be provided with a discharge spout 22 from which the material may be taken to where desired, in any suitable'manner. The screen is preferably inclined as shown, or constructed in an equivalent manner, so that the coarse material which does not pass through, will shake or slide off the same and fall into the hopper 24', which is connected to the chute or discharge spout 24. Grinding or pulverizing rolls 23 or the equivalent, are preferably provided and arranged to grind or pulverize the material to the desired extent. From the spout 24 the material may be cpnducted or carried away in any desired manner.

It will be noted that a stack 25 is provided at the discharge end of the drum. This communicates with stack 27, 26 being a fan or blower or the equivalent, which may be provided if desired, for drawing the heated. gases through the drum. Stack 27 is in communication with stack 27, 28 being a hopper or collector which is preferably provided. The purpose of collector 28 is to collect any fine calcined particles drawn up the stack, and the same being calcined properly are conducted to the'hopper 21 by means of a screw 29, driven by a pulley 30 or their eqivalents. I preferably provide thermometers 16 and 16' to indicate the temperature of the gases and products at the discharge end of the drum, such other thermometers being provided as may be desired.

The operation of the device may be briefly described as follows :-Assuming that heat is generated in the furnace 10 and drawn through the calciner by the fan 26 or by the ordinary draft due to a high chimney or the like, thddrum rotates continuously, and as material is dumped into the hopper 13, for example material such as gypsum rock crushed as desired, the particles being of various sizes, small, medium or large, the same is uniformly and continuously fed from the hopper 13 through chute 12 into the drum 1. Owing to the blades or shovels 9 and the inclination of the drum, if the drum is inclined, the material in the rotating drum is carried to the discharge end, all.

parts being subjected to the heat. As it is carried along, however, it is perfectly and uniformly calcined. The degree of calcination may obviously be controlled by the intensity of thefire in the furnace 10, or hot gases produced and admitted to the drum,

and the time required for the material to pass through the drum which will be governed by the pitch of the drum or shovels and the speed at which it is driven. The

passage of the gases through the drum may particles too coarse to pass through the screen move off andpass through the crusher so that they are evenly and thoroughly pulverized, and a uniform product is the result. Any of the lighter calcined particles that might be drawnup through the stack 25 will fallinto the hopper 28' and be conducted to the hopper 21.

By controllingv the material placed in hopper 13, i. e. the percentages. of fine and coarse, the time and heat, etc., the materials discharged may be varied, depending on the demands for the products. In other words, one or more products may be obtained from one calciner, the products varying in characteristics, being in the desired relative proportions as well as in characteristics.

It will be noted that the process is con-.

tinuous, and the several products, perfectly calcined, are obtained at one calcination, the products having widely different characteristics in their dry bulk, and,in the amount of water which they will carry to bring them to a certain consistency. The material discharged from spout 22 is very fine and not re-ground, consequently this material has a high water carrying capacity, which permits the casting of a mass which is dense in its nature, and of considerable structural strength. The material discharged from the spout 24 has a very large dry bulk, and a small amount of water causes the material so mixed to become stiflt', producing a mass having a very great plastic quality but not very high structural strength. By adding additional grinders and screens (not shown) of different sized mesh, any number of products may be obtained' at one calcination having varied characters.

Having thus described my invention, it is obvious that various immaterial modifications may be made in the same, without departing from the spirit of my invention; hence I do not wish to be understood as limiting myself to the exact form, construction, arrangement and combination of parts herein shown and described or uses mentioned.

What I claim as new and desire to secure by Letters Patent is:--.

1. A method of treating gypsum rock consisting in calcining a mass of gypsum rock made up of fine and coarse particles, then separating the course particles. from the mass, and re-grinding the coarse par-' ticles; whereby two products of different natures are secured.

2. A method of treating gypsum rock,

consisting in passing various sizes of gypsum rock articles through a calciner, and agitating 5'16 same and applying heat thereto during the agitation, then separating the coarser particles from the finer particles and grin ing the former whereby two products of different natures are secured.

3. A method of treating a gypsum rock mass comprising fine and coarse particles to produce at one calcining productshaving varied characteristics, consisting in subjecting a mass of gypsum rock composed of fine and coarse particles to the action of heat, and agitating the same during the heating to calcine all the particles, then separating the particles of the desired sizes from the calcined mass to produce a product of one hygroscopic nature and crushing the remainder of the mass to produce a second products of diflerent natures are secured.

5. The herein described method of manufacturing gypsum products, consisting 1n first coarsely crushing the raw gypsum,-

then calcining the same, then separating the fine material from the coarser, and then further grinding. the coarser material,

whereby. two products of different hygroscopic natures are secured. v 6. The herein described method of manufacturing gypsum products of different hy groscopic natures by a continuous operation which consists iii-calcining the crushed raw material, then separating the fine material.

from the coarse, the fine material providing a product of one hygroscopic nature, and finally grinding the coarse material to provide a product of a different hygroscopic nature.

In testimony whereof, I have hereunto signed my name in the presence of two subscribing witnesses.

Witnesses: Y

RoY W. HILL,

CHARLES I. Com z.

CHARLES R. BIRDSEY. 

